Determination of peptide dissociation constants and Stokes radius at different protonation stages by capillary electrophoresis

Peptide electrophoretic mobility measured by capillary zone\r\nelectrophoresis can be regarded as deriving from the mean of mobilities\r\nof different protonated forms, each one participating according to its\r\ncharge, Stokes radius and relative percentage. The percentage is a\r\nfunction of the peptide dissociation constant and solution pH.\r\nTherefore, mobility modifications due to pH variations can be related to\r\npeptide dissociation constant, charge, and Stokes radius throughout\r\ngeneral binding equations. Thus, not only can peptide dissociation\r\nconstants be measured, but information about Stokes radius modifications\r\nlinked to proton loss can also be obtained with picomoles of peptide.